Estimated blood loss and anemia predict transfusion after total shoulder arthroplasty: a retrospective cohort study

BACKGROUND: Reported blood transfusion rates after total shoulder arthroplasty (TSA) range from 4.5% to 43%, and reported risk factors include race, female sex, prosthesis type (reverse), revision, age, anemia, low preoperative hemoglobin, and number of comorbidities. The purpose of this study was to develop a predictive model for transfusion in anatomic/hemi and reverse shoulder arthroplasty patients and to estimate the transfusion rate in a community hospital setting. METHODS: A retrospective cohort of 265 shoulder arthroplasties (79 anatomic, 182 reverse, and 4 hemiarthroplasties) performed consecutively by 1 surgeon at 1 institution from May 2013 to May 2016 was assembled. Two patients were excluded for insufficient data, leaving 263 patients for analysis. Sensitivity, specificity, area under the curve, and cut points using estimated blood loss (EBL), history of anemia, and preoperative hemoglobin level were calculated, based on a logistic regression model. RESULTS: The overall transfusion rate was 2.3% (6/265). Higher EBL (P = .003), lower preoperative hemoglobin level (P = .030), and history of anemia (P = .088) were predictive of transfusion with a sensitivity of 80.0% and a specificity of 99.6%. In this cohort, patients with a history of anemia had transfusion risk when an EBL of ≥300 mL was combined with a preoperative hemoglobin level <10.9, resulting in a sensitivity of 1.0 and a specificity of 0.96. Factors associated with transfusion in univariate models included arthroplasty for fracture (P < .001), cemented stem (P < .001), length of stay (P < .001), EBL (P < .001), operative time (P < .001), and preoperative hemoglobin (P = .004) and hematocrit levels (P = .004). CONCLUSION: Patients with a history of anemia, a preoperative hemoglobin level <10.9, and an intraoperative EBL ≥300 mL are at high risk for transfusion after TSA.